Early June flooding leaves some skeptical

Jason Bragg was in the finishing stages of completing his new home at Les Maisons Sur La Rouge when floodwater surrounded his house. He was able to keep water from coming in with sandbags and with help from a lot of people. Officials say another flood may be coming.(Photo: Henrietta Wildsmith/The Times)Buy Photo

A day after Caddo-Bossier emergency responders alerted residents of Red River's anticipated July 1 34-foot crest, the National Weather Service forecast on Friday a lower crest of 30.5 for the same time frame.

Later in the day, NWS ran its model again and got a projected crest of about 32 feet.

Considering what happened earlier this month when Red River spilled over its banks, not everyone is confident in the projections.

Yet, some are.

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Jason Bragg Interview

The river ended up in Lee Harvill's River Bluff home.

"It's obvious, between the Corps of Engineers and the National Weather Service, they really don't know what it's going to do. It's sad but true. God bless them," Harvill said. Crews were cleaning up his home Thursday.

NWS projections changed seven times in two weeks. The river finally crested at 37.14 feet.

Last week, emergency responders told residents to prepare for the anticipated 34-foot crest. By Friday afternoon, there were two numbers circulating — the 34-foot contingency projected earlier in the week and the 32-foot crest forecast of Friday afternoon.

"There's been a little bit of confusion and stuff about what the values are going to be in the Shreveport," said Jeff Graschel, service coordination hydrologist at NWS's Lower Mississippi River Forecast Center in Slidell.

There's still a potential for Red River to reach major flood stage of 33 feet, Graschel said. Models used to forecast the river have been adjusted to include new data that should allow for better predictions, but it hasn't killed the uncertainty.

Who trusts the projections?

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Bill Carrier used sandbags to keep his house dry from floodwaters. A new flooding threat looms.(Photo: Henrietta Wildsmith/The Times)

In Shreveport, residents are being told to "hold tight," keep sandbags in place and stop extensive cleanup efforts until there's absolute certainty crest projections hold.

Friday's early morning forecast allowed for a little breathing room, but given the last two weeks Shreveport officials aren't letting their guard down, said Brian Crawford, the city's chief administrative officer. The new forecast will bring more cause for concern.

Since then, the forecast has the river cresting at 32 feet.

"With the challenges we had last time with predictions, we were already preparing for a worst-case scenario of returning to a 37-foot level and, if that happened, making sure those neighborhoods that would be affected and impacted had all the resources the city could provide at their disposal," he said.

Officials are erring on the side of caution, Crawford said. They're wondering how bad the situation can get while making sure sandbags, workers and trucks are ready to go if there's a repeat of the first flood.

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ABOVE: Houses in Allendale when floodwater first started impacting the city. LEFT: The same site a week later.(Photo: PHOTOS BY Henrietta Wildsmith/The Times)

"I'm not a hydrologist, and we don't have one working for the city. So in a lot of ways, in municipal and emergency management operations we're completely at the mercy of those forecasts," he said.

Government officials and first responders have more than a week to prepare. During that time, the river is expected to go down before it rises again.

Caddo Parish Commission president Lyndon B. Johnson said the parish will keep sandbags in place and plans to use the National Guard and inmates for help if needed. The parish also has plans to provide Facebook updates, he said.

"If you flooded before and had mud in your home, I would stop what I'm doing because more than likely you're going to get water in your home again," Whittington said.

Walker advised residents to leave their sandbags in place. Sandbags were made available over the weekend.

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Bill Carrier stands in the same spot (bottom photo) where he stood one week before when a sandbag wall was the only thing saving his house from floodwater in North Bossier.(Photo: Henrietta Wildsmith/The Times)

Mike Steele, Governor's Office of Homeland Security and Emergency Preparedness spokesman, said GOHSEP is not a first response agency but is keeping its crisis action team activated if local governments request additional assistance.

Sandbags and bottles of water are stationed at distribution points so they can be quickly delivered to locations in need. The first meeting with the NWS took place Friday — earlier than expected.

Local governments haven't requested state assistance, Steele said.

The flood kept Jason Bragg from moving into his home. He was one week away from completing construction on his Les Maisons Sur La Rouge residence when he had to stop.

Bragg will prepare by re-stacking the wall around his home.

"We prepared for a certain level of rise. I understand prediction levels changed every day by feet, at some point, and that's the thing that hurt us," he said.

The Science

When Red River flooded this month, 1990 data was used as reference points even though up-to-date data was available.

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"Communities throughout the state rely heavily on timely and accurate information from Army Corps and NWS on how threats from natural disasters will potentially impact life and property," the letter reads. "The constant change in crest predictions presented significant challenges for state and local first responders."

The NWS uses the Community Hydrologic Prediction System to view hydrologic and hydraulic models to forecast river levels. The models are calibrated based on historical data.

The models account for rainfall, both forecasted and observed, soil conditions and other elements key to forecasting. The U.S. Geological Survey collects historical data used in the models, several hydrologists said.

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TOP: Floodwaters from the Red River have gone past the Clyde Fant Parkway and up to Sci-Port. BOTTOM: The same site a week later.(Photo: Henrietta Wildsmith/The Times)

Graschel said outdated models NWS uses for forecasting relied on the historical data instead of the weekly measurements the Army Corps usually provides. One of the issues was that stage levels around 34 to 37 feet hadn't been seen since the 1940s, he said.

"The channels changed since then," Graschel said. There was nothing current in the present-day discharge levels that would tell where the values should have been at 34 or 37 foot levels, he said.

Discharge measurements the Army Corps reported back had a different rating curve, or the relationship between flow to stage, and did not match historical data.

"That's when we had to start making adjustments and increase our forecast for the Shreveport area," Graschel said. "Because of the channel changes and stuff, we were a little bit into unknown territories as to exactly what the peak flows would be at Shreveport."

Future events will be better measured from a rating curve stance, and they now have a better understanding of the discharge levels up to 37 feet, he said.

They've also learned Red River at Shreveport has less capacity to hold water flowing through it, he said. But given the adjustments made during the first flood, Graschel said, NWS models now should be able to make better predictions about the river's crest at Shreveport.

But that's only for 37 feet or below. Anything higher still would be problematic.

Trusted science?

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Homeowner Randy Wright of River Bluff deals with the aftermath of the flooding in north Bossier.(Photo: Henrietta Wildsmith/The Times)

Gary Hanson, a hydrologist at LSUS Red River Watershed Management, said forecasting rivers is not an exact science and is continually being improved. They rely on a constant incoming of up-to-date data to determine what the river will do, but historical data is taken into consideration, too.

"We continue to add in the data as we get it, and move forward with it," Hanson said. "In some cases you have to have an event like this occur to get the data to work with, or a data point. If the only data point like this goes back to 1945, you don't have a lot to work with."

Hanson said many factors key into what makes this flood so different than 1945.

The amount of infrastructure along the river is one of them. Hanson said water is running off over roads and buildings instead of soaking into the soil, putting more water in Red River.

The other factor is capacity. Red River is very narrow between Caddo and Bossier, giving it a higher velocity and causing more sediment to be moved along its banks. The amount of vegetation and concrete and steel structures also play into this, Hanson said.

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TOP: A house in Les Maisons Sur La Rouge where the only thing keeping the water from getting into the house was a wall of sandbags. BOTTOM: The same site a week later.(Photo: PHOTOS BY Henrietta Wildsmith/The Times)

"It's always a moving target because when you look at a map you'll realize how out-of-date it is, even after only a year," Hanson said.

Army Corps-Vicksburg Chief of Public Affairs Greg Raimondo has unwavering confidence in the data and the new model.

So much so that the Army Corps plans to carry out the exact same plan it had in place during this month's earlier flood.

He's convinced if the Army Corps in Tulsa and Little Rock can keep releases of water to 130,000 cubic feet per second at Fulton, Arkansas, every location downstream will be below flood stage, or 30 feet. That includes Shreveport.

But the water going over Denison Dam at Lake Texoma has to be closely watched, he said.

"That's the exact same thing we did during the first event. There was just a lot more rain and it was in different spots throughout the whole basin," he said.

When asked why Caddo-Bossier residents should trust the plan, Raimondo deflected the question of trust from the Army Corps to NWS — if residents want a reason to believe the next predictions, they should ask the scientists.

"We're attempting to control this river using the reservoirs and keep the flow at 130,000 feet per cubic second. That's the intent," he said.

How do you plan?

There were still many uncertainties as of Saturday. A crest has not been identified for the official forecast as peak conditions at Lake Texoma still are being monitored, according to the NWS in Slidell.

The 32-foot crest the models predicted Friday were based on conditions at Texoma's Denison Dam at that time. The predicted crest had not changed.

Graschel said NWS still has a few days to monitor peak conditions at Lake Texoma and to fine tune its forecast. Meanwhile, emergency responders are still planning for a 34-foot crest.

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TOP: Floodwaters from Red River have gone past the Clyde Fant Parkway and up to Sci-Port. BOTTOM: A week later.(Photo: PHOTOS BY Henrietta Wildsmith/The Times)

"It could be worse, but we know where 34 will go now," said Bossier Sheriff Julian Whittington during a news conference late Friday. "We were actually up there on the ground ... two weeks ago at 34 so we've got a good idea on who that will affect."

The discrepancy in crest numbers confused Raimondo Friday who said the Army Corps was told the river would crest at 30.5 feet on July 1.

"I don't know where this number keeps coming from. The National Weather Service put out today their prediction of 30.5," he said.

Raimondo began making calls to other people in the Army Corps, to the National Weather Service office in Shreveport and Slidell to find where the break in information occurred.

Graschel said the local NWS office quoted the 34-foot forecast to Caddo-Bossier officials as a possibility earlier in the week.

Still, he said more engineering needs to be done.

At Les Maisons, Braggs said he feels prepared.

"We're strong. We've learned a lot of lessons," said Bragg. "We know how to do it bigger and better next time. We are in the process of continuing to build the house and get it done."

How rain water gets to Red River

Water can come from precipitation, melting snow and ice, and small tributaries.

When rain falls and hits the ground it either infiltrates the ground and becomes groundwater, runs off, evaporates, or is absorbed into plants through transpiration.

The system the NWS uses

National Weather Service River Forecast System

Hydrologic models — representation of the water cycle

Hydraulic models — used to take readings in stream and around river structures like locks and dams

Three components of a model

Calibration system — shows historic data (these aren't always reliable because of changes to a river system over time)